In certain environments, such as in flight vehicles and projectiles, certain structural members, such as fins, are required to be held in a secured, retracted position for storage, transportation, or other pre-deployment requirements and are required to be quickly and reliably released during operation. Locking mechanisms are typically used to provide such securing and release of the structural members. For example, in certain applications such as smart bombs with movable fins (for guidance), missiles with movable fins, and satellite or space vehicles and equipment with deployable panels (e.g., solar panels), a locking mechanism biases the fins or panels towards their retracted positions with a large force, typically a spring force. Actuation of the locking mechanism causes the fins or panels to be released to a deployed position.
One type of locking mechanism, such as a ball-detent locking mechanism, includes a housing having a plunger spring compressed into a locked position. In the locked position, a portion of the plunger holds one or more balls in a position where they lock a further element (e.g., moveable fins or structural members) in a locked position. For example, when in the locked position, the plunger holding the balls has a recess or recesses proximate to but not in alignment with one or more balls. As the plunger moves axially to the release position, the recess or recesses of the plunger align with and receive the balls, allowing the balls to move from the housing detents, and thereby allow expansion of the spring to an open position to release the lock on the element being held. The plunger's linear motion can be either manually driven or electrically driven such as by use of a solenoid.